Zigzag stitch attachment for sewing machines



July 28, 1959 c. H. wURKr-:R '2,896,563

ZIGZAG S'lll'l'C-I ATTACHMENT FOR SEWING MACHINES Filed Deo. 5. 1956 M J F/af /A/VEA/r@ C19/PL H. Wal? 5R United States Patent O ZIGZAG STITCH A'ITACHNLENT FOR SEWING MACHINES Carl H. Wrker, Aistaig am Neckar, Germany Application December 5, 1956, Serial No. 626,370

Claims priority, application Germany June 19, 1956 7 Claims. (Cl. lll- 160) The present invention relates to attachments for sewing machines which enable the perfomance of zigzag stitch, buttonhole, and embroidery work with ordinary sewing machines performing only vertical movements of the needle bar. These attachments are provided with a tissue or cloth displacing lever or feed bar which is swung back and forth in an approximately horizontal plane about its pivot by a gear driven by the needle bar of the sewing machine, thereby imparting to the tissue or fabric movements cross-wise to the feed direction of the sewing machine. The arc length of the deection executed by the end of this cloth displacing lever engaging the cloth by means of a presser or cloth displacing foot determines the width of the zigzag stitches, the so-called overstitch.

Since the width of this overstitch must be made smaller or greater according to the particular work at hand, the pivot for the cloth displacing lever is provided in known attachments on a slide at the bottom plate of the gear housing adapted for displacement in the longitudinal direction thereof. By shifting the pivot, the length of the arm of the cloth displacing lever engaging the cloth, can be shortened or lengthened as the desired stitch width requires. The setting slide carrying said pivot has been secured in the desired position in known attachments at the rear end of the extended gear housing bottom plate by. means of a clamping screw. Adjusting a changed stitch width was for this reason somewhat complicated.

It has also been proposed heretofore, to couple the setting slide with an adjusting lever which is articulated in position at the bottom of the gear housing. Hereto fore the adjusting lever had a single arm and its pivot was arranged laterally of the setting slide. The setting slide was rectilinearly and rigidly guided in its longitudinal direction, so that, `on the one hand, the pivot of the cloth displacing lever attached to it, was guided in a longitudinal slot of the gear housing bottom and, on the other hand, the coupling bolt connecting the setting slide with its adjusting lever, :was likewise guided in a 1ongitudinal slot of the gear housing. Because of the straight movement of the setting slide, the coupling bolt could not be fastened rigidly to the adjusting lever extending crosswise to the setting slide but had to be guided in a longitudinal slot also at this lever.

Since the guide slots for the coupling bolt in the gear housing bottom and in the adjusting lever crossed, there occurred between them and the coupling bolt considerable friction, which rendered the operation of the over-1 stitch adjusting device difficult.

The invention avoids this and other disadvantages heretofore encountered in that the setting slide is pivotable about the pivot of the cloth displacing lever, which pivot is displaceable in a known manner parallel to the longitudinal center line of the gear housing,` and is coupled with its adjusting lever fixed on the gear housing by a lever arm of constant length. It is advantageous to design the adjusting lever as a two-arm lever whose Xed pivot is arranged approximately on the longitudinal center line of the gear housing bottom and whose one arm is articulated to an enlargement of the setting slide projecting laterally over the gear housing. The pivot of the adjusting lever fastened in the gear housing bottom passes through a slot in the setting slide, whose end edges limit the range of adjustment of the setting slide.

It is an important advantage of the invention that operation of the setting device is greatly facilitated due to reduced friction between the setting slide and the adjusting lever.

These and other object of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawing, showing preferred aspects of the invention.

An embodiment of the invention there is represented in the attached drawing.

Fig. l shows a side view, partially broken away, of an attachment according to the invention in operative position.

Fig. 2 shows a top view of the setting slide with adjusting lever and a portion of the gear housing bottom supporting the pivot pin for the adjusting lever.

Figs. 3 and 4 each show a vertical cross-section taken along line III-Ill of Fig. 2, a stop provided at the adjusting lever occupying two different operative positions.

Referring now more particularly to the drawing, there is disclosed a zigzag stitch attachment which includes a support means in the form of a gear housing 1 fastened by means of a clamping member 2 to the presser bar 3 of a sewing machine (only partly seen). In the gear housing l is mounted for rotation a control drum 4, which by means of a switch member 5 and a switch mechanism consisting of pawl 6 and ratchet wheel 7 is set into intermittent rotation by the up and downward movement of the needle bar 8 of the sewing machine. The control drum 4 serves to drive a cloth displacing lever or feed bar 9, 'which is arranged under the bottom plate 10 of the housing 1 and carries a presser foot 12 at its front end provided with a bearing fork member 11. The cloth displacing lever 9 carries at its rear end a driving or entraining pin 13, which is provided with a friction-reducing roller 14. The latter reaches Without play through a passageway or slot of the housing bottom plate 10, the control cam of the drum 4 and is set by the latter into reciprocal movements extending crosswise to the longitudinal center line of the housing.

The cloth displacing lever 9 swings about a pivot 15, which is riveted to the front end of an adjustment slide 16. On the pivot 15 a slide ring 17 is loosely and rotatably mounted, pivot 15 being displaceable ina longitudinal slot 18 of the cloth displacing lever 9. The pivot 1S itself engages without play through a longitudinal slot 19 of the housing bottom plate 10 and carries at its upper end a latch 20' which extends crosswise to the longitudinal slot 19 of the housing bottom plate 10' and serves to retain the cloth displacing or feed bar lever 9 and adjustment or setting slide 16 at the housing bottom plate in an easily detachable manner.

At its rear end slide 16 is widened to form, a plate 16. On it and on one side of the longitudinal center line A-A of housing 1 forming the support means, anyadjusting lever '21 is articulated by means of a hinge bolt 2,2 forming hinge means. The adjusting lever 2.1 is mounted for oscillation about a pivot 23 which is fixed in the rear end of the housing bottomplate 10 and whose wide head 24 forms at the same time a support for the slide 16 and the adjusting lever 21 and retains them by. means of a washer 25 on the housing bottom 10. Slide 16 is provided with an arched slot 26 for the free passage of pivot 23. The ends of the arched islot 26 strike in the extreme end positions of the slide 16, which is longitudinally displaceable relative to the housing bottom, against said pivot 23 and thus limit the range of adjustment of the setting slide.

The upper end Vof the pivot 23 is provided with a screw thread 23' and can be screwed from` below into a four-square ilat nut '27, whose key faces are secured without rotation between the legs lil of the profile of the housing bottom lt) which is U-shaped at this point (Fig. 3). The fact that the four-square nut`27 is retained without rotation when the pivot 23, 23 is being screwed in facilitates assembly, which requires no other tool than Va screw driver. Between the four-square nut 27 and the housing bottom 1t) or respectively the U-shaped legs v10. thereof the1e`is `advantageously arranged a guard cap 28 made of steel and a plate spring or Washer 29. A lock nut 3l) is designed as a rounded cap nut and provided with a slot 30' so that it can also be tightened without ya wrench by means of a screw driver. p

The side of the setting `slide plate 16 located opposite the hinge bolt 22 is provided with an edge 31 which extends along a circular arc whose center lies in hinge 22. This edge, by a recess 31 concentric to it, is provided with two abutments or stops 32` and 33 defining said recess. These stops serve to limit the stroke of the adjusting lever 2l. At its handle end the adjusting lever 21 is provided with two flaps 34 bent upward, which serve as a bearing for a rivet pin 35 on which a cam disk 36 is mounted for rotation (Figs. 3 and 4).

The cam disk 36 is secured against unintentional displacement by the friction of a disk or plate 'spring 37 and is provided at its edge with a notch 38. The latter is shaped so that a projecting locking lug 39 is formed which in the position of the cam disk 36 shown in Fig. 3 cooperates with the stops 32 or 33 of the setting slide 16. When the adjusting lever 2l is pivoted to the right until the locking lug 39 rests against stop 32, the setting slide 16 is displaced to the left. Consequently the arm of the cloth displacing ylever 9 carrying the presser foot l2 is shortened and adjusted to a narrow stitch width, as required particularly for buttonhole bordering stitches. if, however, the Yadjusting lever 2l is pivoted to move in opposite direction Ytoward the left until the locking lug 39 strikes against the stop 33, then the setting slide 16 is adjusted to a large stitch width, as required for buttonh'ole lock stitches.

In the position of the cam disk 36 shown in Fig. 4, the other edge of notch 38 rests on the top side of the adjusting lever 2li and the locking lug 39 is in a position in which it cannot be reached by the stops 32, 33.

Now the adjusting lever 2l can be set to still smaller or respectively larger stitch widths beyond the stops 32 and 33.

The range of adjustment is then limited only by the fact that the xed pivot 23 of the adjusting lever 2l strikes against the ends of the arched slot 26, as hereinabove described.

In Vorder to facilitate ,the setting of adjustment 'lever 21, a setting scale could be provided along the archshaped edge 31. But since this side of the sewing attachment, on which Vsaid arch-shaped edge 3l is provided, is usually diiiicult to see, the setting scale 40 is provided, according to the invention, on the opposite side cn which the hinge bolt 22 is arranged. In order that the divisions of said setting scale dllfmay be located with clear distances from each other and not too close together, adjusting lever 2l is provided with two setting edges 4l and 42. The rst-named setting edge 41 is inclined against the center line of adjusting lever 21 and cooperates with the scale divisions l and 2 for small stitch widths, while the second setting edge 42 extends approximately parallel tonsaid center line of adjusting 1e`ver`21 and cooperates with therscale divisions 3 and 4 for large stitch widths. j

From the foregoing it will be seen that there has been provided, in accordance with a broad View of the invention, a zigzag stitch attachment for use in connection with sewing machines, comprising support means having a center line, an adjusting lever having spaced ends, rst pivot means xedly arranged on said support means, said adjusting lever being disposed on said first pivot means for pivotal movement thereabout, a setting slide, hinge means carried by said adjusting lever adjacent one of said ends thereof, whereby the part of said adjusting lever between said first pivot means and said hinge means constitutes a lever arm of constant length, said setting slide being articulated to said hinge means, second pivot means carried by said setting slide, and a cloth displacing lever slidably accommodating said second pivot means for movement longitudinally of said cloth displacing lever, said second pivot means extending into and being guided in said support means for slidable displacement substantially lengthwise of saidV center line of said support means, whereby the location of said second pivot means and thus the pivot axis and effective length of said cloth displacing lever may be adjusted longitudinally of the latter by pivotal displacement of said adjusting lever about said rst pivot means land consequent displacement of said setting slide substantially longitudinally of said cloth displacing lever. Various changes and modifications may be made Without departing from the spiritand scope of the present invention and it is intended that such obvious changes and modications be embraced by the annexed claims'. Having thus described the invention, what is claimed Y as new and desired to be secured by Letters Patent, is:

l. A zigzag stitch attachment for use in connection with sewing machines, comprising support means having center line, an adjusting lever having spaced ends, iirst pivot mean iixedly arranged on said support means, tsaid adjusting lever being disposed on said rst pivot means for pivotal movement thereabout, a setting slide, hinge means carried by said adjusting lever adjacent one of said ends thereof whereby the part of said adjusting lever between said irst pivot means and said hinge means constitutes a lever arm of constant length, said setting lslide being articulated to said hinge means, second pivot means carried by said setting slide, and a cloth displacing lever slidably accommodating said second pivot means for movement longitudinally of said cloth displacing lever, said second pivot means extend- 'ing into and being guided in said support means for slidable displacement substantially lengthwise of said center line of said support means whereby the location of said second pivot means' and thus the pivot axis and elfective length of said cloth displacing lever may be adjustedrlongitudinally of the cloth displacing lever by pivotal displacement of said adjusting lever about said iirst pivotmeans and consequent displacement of said setting slide substantially longitudinally of said cloth displacing lever, said setting slide being provided with a 1 pair of spaced abutments, said adjusting lever having a second `arm remote from said constant length lever arm provided with stop means selectively shiftable to a first position for engagement with said abutments and to a lsecond position bypassing said abutments upon pivotal movement of said adjusting lever.

2. An attachment according to claim l, said setting Aslide being provided with an arcuate slot slidably accoinmodating said lirst pivot means, the opposite ends of said arcuate slot `when abutting against said rst pivot means defining the limits of the range of adjustment of said second pivot means resulting from displacement of said setting slide to thereby predetermine the maximum and minimum stitch 'widths attainable.

3. An attachment according to claim 2, said 'lirst pivot means comprising a headed screfwl extending through said setting slide, said adjusting lever 'and said supportmeans, with said head engaging said setting slide from below, a nut threaded onto said screw 'from above said support means to retain said screw on said support means, and means on said support means engaging said nut and preventing rotation thereof.

4. An attachment according to claim l, said setting slide being provided at a portion remote from and opposite to the articulation thereof to said hinge means `with an arcuate notch centered at the axis of said hinge means and terminating in spaced end edges constituting said abutments, respectively.

5. An attachment according to claim 1,- further cornprising -a disk rotatably carried by said adjusting lever adjacent the other of said ends thereof, said stop means being arranged on said disk.

6. An attachment according to claim 5, said disk being arranged for rotation about a horizontal axis and being provided with a peripheral notch terminating in upper and lower edges with said lower edge constituting said 7. An attachment according to claim 1, further comprising a setting scale provided on said setting slide adjacent the articulation thereof to said hinge means, said adjusting lever being provided with indicator edges angularly disposed with respect to each other for cooperation with respective portions of said setting scale.

References Cited inthe le of this patent UNITED STATES PATENTS Sharenow et al. Dec. 2, 1952 Ayres Jan. 24, 1956 

